Track and field is a sport in which athletes compete in running, jumping, and throwing events. The hurdles are two events that combine running and jumping. In the hurdles, the athletes run in designated lanes and jump over spaced apart hurdles in between the start and finish. A hurdle consists of a base having two legs, two uprights, and a horizontal gate board (sometimes spelled “gateboard”). In the first hurdle event (commonly known as the high hurdles), athletes run about 100 meters and jump over relatively high hurdles. In the second hurdle event (commonly known as the low or intermediate hurdles), athletes run about 400 meters and jump over lower hurdles. The height of the hurdle in each of the events varies depending upon the age and sex of the athletes. For versatility and economy, most hurdles are adjustable in height. Adjustable hurdles contain movable gate tubes (also known as risers) that telescope relative to uprights. The gate board is attached to the gate tubes.
A hurdle is designed to tip over if the athlete contacts it. The force at the gate board required to tip the hurdle over is commonly known as its pull over weight. The pull over weight is a function of the height of the hurdle. Other things being equal, the pull over weight decreases as the height of the hurdle increases. Most hurdles contain counterweights in the base to achieve the desired pull over weight. To maintain a relatively constant pull over weight as the height of the hurdle changes, many modern hurdles incorporate counterweights that move in the legs of the base. As the height of the hurdle increases, the counterweights are moved further away from the uprights and, as the height of the hurdle decreases, the counterweights are moved toward the uprights. In some hurdles, the counterweights are moved manually. In other hurdles, the counterweights are connected mechanically to the gate board so that they move automatically as the gate board is moved.
Hurdles with automatically movable counterweights connected to the gate board are disclosed in Dellinger et al., U.S. Pat. No. 4,749,187, Jun. 7, 1988, and Watry et al., U.S. Pat. No. 7,438,668, Oct. 21, 2008. Both the Dellinger et al. and the Watry et al. hurdles contain counterweights inside the legs of the base that are connected to the gate board by a mechanical system consisting of cables, pulleys, and coil springs. In the Dellinger et al. hurdle, the coil springs are located in the legs whereas in the Watry et al. hurdle, the coil springs are located in the uprights. There are two disadvantages associated with coil spring counterweight systems. First, the coil springs apply a downwardly directed force to the gate tubes and gate board. Raising the gate boards on these hurdles require the force of the coil springs to be overcome. Second, hurdles are subjected to rough treatment and the coil springs are the component that malfunctions or breaks most frequently. The coil springs are difficult to repair because of their location.
Lindstrom, U.S. Pat. No. 8,968,157, Mar. 3, 2015, discloses a hurdle with automatically movable counterweights connected to the gate board. The Lindstrom hurdle uses a system of gear wheels and racks in the legs of the base instead of a coil spring system. The gear wheels and racks in the Lindstrom hurdle are also prone to malfunction when the hurdle is subjected to rough treatment.
Accordingly, a demand exists for an improved hurdle. In particular, a demand exists for an improved and more durable hurdle that requires less force to raise the hurdle and that contains automatically movable counterweights without coil springs, gear wheels, and racks.